(1) Field of the Invention
The invention relates to a pneumatic proportioning and transport procedure for solids between an atmospherically pressurized storage container and a pressurized chamber, as well as apparatus for the implementation of such a procedure.
(2) Brief Description of the Prior Art
Although it is not restricted to this, the present invention concerns the handling of pulverized solid materials in the iron and steel industry such as lignite powder with a view to injection thereof into blast furnaces. The present invention also has applicability to the transport of powdered ore for injection into a direct reduction installation reactor. Accordingly, the invention shall be described by way of illustration in reference to such iron and steel applications.
The utilization of lignite as a fuel for the maintenance of the reduction process in blast furnaces is a very recent technique, the mastering of which is of particular interest to the extent that it allows oil products to be replaced by lignite which is an inexpensive product of which there are still large reserves. Unfortunately, this technique has remained at the theoretical stage or, at the most, the experimental stage. The reason for previous lack of commercial application of the technique in question is precisely that, to date, the technical means necessary for the injection of large and proportioned quantities into pressurized chambers, such as a blast furnace, have not been available.
The problem of the transport of pulverized coal and ore in the case of direct reduction plants, although being slightly different, is nevertheless comparable to the extent that, while such plants already exist, costly and cumbersome mechanical transport systems must be used for horizontal and vertical transport and it has not yet been possible to benefit from the advantages offered by pneumatic transport systems which are well known in themselves. Once again the reason is that it is a question of injecting large quantities into a pressurized receptacle in a controlled manner and in a proportioned quantity. Previously available pneumatic systems do not comply simultaneously with all these criteria, a condition which is, however, sine qua non for implementation on an industrial level in the applications concerned.